Black hole responsible for Cosmic Searchlight

Related Stories

Images from NASA's Hubble Space Telescope have enabled scientists from the Space Telescope Science Institute (STSI), to identify a supermassive black hole as the energy source powering an extragalactic jet, studied by astronomers for over eight decades.

The M87 galaxy, one of many giant elliptical galaxies in the Virgo cluster, was first recognised by astronomer H. D. Curtis in 1918, due to "a curious straight ray" protruding from its centre.

This ray - likened to a 'cosmic searchlight', has been identified as a black-hole-powered jet of electrons and other sub-atomic particles, which are travelling at nearly the speed of light.

The jet originates in the disk of superheated gas swirling around this black hole, which astronomers believe has swallowed up a mass equivalent to 2 billion times the mass of our Sun. The jet is propelled and concentrated by the intense, twisted magnetic fields trapped within this plasma.

The light that we see (and the radio emissions detected since the 1950s) is produced by electrons twisting along magnetic field lines in the jet, a process known as synchrotron radiation, which gives the jet its bluish tint.

STSI scientists said, whenever a massive black hole is feeding on a particularly rich diet of disrupted stars, gas, and dust, the conditions are right for the formation of a jet.

The accompanying image was collected in 1998 from a distance of 50 million light-years - a distance too great for the identification of individual stars. The dozens of star-like points swarming about M87 are actually clusters of hundreds of thousands of stars.

An estimated 15,000 globular clusters formed very early in the history of this galaxy and are older than the second generation of stars, which huddle close to the centre of the galaxy.